Devices and methods for abluminally coating medical devices

ABSTRACT

A stent crimping and coating apparatus is disclosed. The apparatus includes a plurality of crimping blades positioned in a radial array and collectively forming a central crimping lumen, wherein the plurality of crimping blades radially movable to alter the diameter of the central crimping lumen. Each of the crimping blades includes a first surface configured to at least in part define the central crimping lumen. One or more of the crimping blades includes a fluid channel extending therein and a plurality of openings in fluid communication with the fluid channel. The plurality of openings are located at the first surface of the one or more crimping blades and adapted to discharge a fluid into the central crimping lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/130,846, filed on May 30, 2008, the entire disclosure of which isincorporated herein by reference.

FIELD

The present disclosure relates generally to the field of coating andcrimping stents or other medical devices. More specifically, the presentdisclosure pertains to apparatus and methods for abluminally coatingstents or other medical devices mounted onto a delivery device.

BACKGROUND

Medical devices such as stents, stent grafts, and vena cava filters areoften utilized in combination with a delivery device for placement at adesired location within the body. A medical prosthesis such as a stent,for example, may be loaded onto a stent delivery device such as aballoon catheter and then introduced into the lumen of a body vessel ina configuration having a reduced diameter. Once delivered to a targetlocation within the body, the stent may then be expanded to an enlargedconfiguration within the vessel to support and reinforce the vessel wallwhile maintaining the vessel in an open, unobstructed condition. In somemedical procedures such as a percutaneous transluminal coronaryangioplasty (PTCA), for example, the stent may be deployed and expandedwithin a vessel adjacent to the location where a lesion has been removedto prevent restenosis or prolapse of the vessel at that region. Thestent may be either self-expanding, or alternatively, may be manuallyexpanded by the inflation of a balloon on the delivery device.

Inflation expandable stents are typically secured to the ballooncatheter in a reduced diameter configuration or profile prior to theiruse. In some techniques, for example, the stents are loaded onto theballoon and then inserted into a crimping device which applies aninwardly directed radial force to the stent. In some techniques, theballoon may be heated to a temperature above the glass transitiontemperature of the balloon material, causing the balloon material toflow and attach or mold to the stent material. In some embodiments, anadhesive material having a melt point below that of the balloon materialmay also be used in some cases to further adhere the stent to the outersurface of the balloon.

The coating of stents is often performed in a separate step prior tobeing crimped onto the balloon catheter. In some techniques, forexample, the entire surface of the stent may be coated by placing thestent in a dip bath containing a drug coating material such as Rapamycinor Heparin. Once coated, the stent is then crimped onto the ballooncatheter in a later step using a combination of pressure and heat. Insome cases, the application of pressure to the stent during the crimpingprocess may interfere with the drug coating material. The loading of thestent onto the balloon catheter may result in frictional forces exertedon the stent that can cause damage to the underlying coating on thestent, in some cases resulting in chipping of the drug coating. Theapplication of heat to the stent may also cause changes in the chemicalcomposition of the drug coating material and may create thermal cracksin the coating, limiting the types of drug coatings that can be used.Accordingly, there is a need for new apparatuses and methods for coatingand crimping medical devices onto delivery devices.

BRIEF SUMMARY

The present disclosure pertains to apparatus and methods for abluminallycoating stents or other medical devices mounted onto a delivery device.An illustrative crimping apparatus can include a number of movablecrimping blades forming an aperture for receiving a medical device suchas a stent. One or more of the crimping blades can include a fluidchannel in fluid communication with a fluid reservoir. During crimping,a number of openings in the blades can be used to abluminally deliverfluid onto the medical device. In some embodiments, for example, theopenings in the blade can be utilized to spray or extrude a drug coatingmaterial onto the stent during the crimping process.

An illustrative method of coating a medical device can include providinga crimping apparatus including a plurality of crimping blades positionedin a radial array and collectively forming a central crimping lumen. Theplurality of crimping blades is radially movable to alter the diameterof the central crimping lumen. One or more of the crimping bladesincludes a fluid channel extending therein and a plurality of openingsin fluid communication with the fluid channel. A balloon of a ballooncatheter and a stent surrounding a portion of the balloon may bepositioned in the crimping lumen of the crimping apparatus. Theplurality of crimping blades may be radially contracted toward the stentto thereby crimp the stent onto the balloon. At least a portion of thestent may be coated with a fluid by discharging a fluid into thecrimping lumen and into contact with the stent from the plurality ofopenings. The plurality of crimping blades may be radially retractedaway from the stent, and the balloon and crimped stent may be removedfrom the crimping lumen of the crimping apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative apparatus for crimpingand coating a medical device;

FIG. 2 is a perspective view of the apparatus of FIG. 1 including amanifold for distributing a fluid to the crimping blades;

FIG. 3 is a perspective view showing an illustrative crimping bladehaving a number of openings along its length;

FIG. 4A is a side cross-sectional view showing the crimping blade ofFIG. 3 along line 4-4;

FIG. 4B shows an alternative embodiment of the crimping blade of FIG. 3along line 4-4;

FIG. 4C shows an alternative embodiment of the crimping blade of FIG. 3along line 4-4;

FIG. 5 is a transverse cross-sectional view showing the crimping bladeof FIG. 3 along line 5-5;

FIG. 6 is an alternative transverse cross-sectional view of the crimpingblade of FIG. 3 along line 5-5 showing a sponge inserted into the fluidaperture;

FIG. 7 is a perspective view showing another illustrative crimping bladehaving a slot formed along the length of the blade;

FIG. 8 is a perspective view showing another illustrative crimping bladehaving a number of larger openings located at opposing ends of thecrimping blade;

FIG. 9 is a perspective view showing an illustrative composite crimpingblade;

FIGS. 10-13 illustrate a method of crimping a stent onto a balloon of astent delivery catheter and coating the stent on the balloon;

FIG. 14A is a perspective view showing a coated stent attached to aballoon delivery catheter;

FIG. 14B is a perspective view showing another embodiment of a coatedstent attached to a balloon delivery catheter;

FIG. 15 is a cross-sectional view of a crimping apparatus including astent and balloon delivery catheter positioned therein;

FIGS. 16A and 16B illustrate the crimping blades of a crimping apparatusin a radially retracted position;

FIGS. 17A and 17B illustrate the crimping blades of a crimping apparatusin a radially contracted position; and

FIGS. 18-21 illustrate another method of crimping a stent onto a balloonof a stent delivery catheter and coating the stent.

DETAILED DESCRIPTION

The following detailed description should be read with reference to thedrawings. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of thedisclosure. Although examples of construction, dimensions, and materialsare illustrated for the various elements, those skilled in the art willrecognize that many of the examples provided have suitable alternativesthat may be utilized. Moreover, while the illustrative apparatuses andmethods are described with respect to the coating of stents and crimpingof stents onto a balloon of a stent delivery catheter, it should beunderstood that other medical devices may benefit from one or more ofthe features disclosed herein. Examples of other medical devices caninclude, but are not limited to, grafts, stent-grafts, and vena-cavafilters.

Referring now to FIG. 1, an illustrative crimping apparatus 10 inaccordance with an illustrative embodiment will now be described. Thecrimping apparatus 10, illustratively a stent crimping and coatingapparatus for crimping a stent onto the balloon of a balloon deliverycatheter, can include a crimping section 12 having a number of movableblades 14 radially disposed about a central crimping lumen 16. In theillustrative embodiment depicted in FIG. 1, for example, the crimpingsection 12 includes fifteen blades radially disposed about the lumen 16.The crimping apparatus 10 may be equipped with a greater or lessernumber of crimping blades 14, however, depending on the size andconfiguration of the stent to be inserted therein. The crimping blades14 may be made of a suitably hard material such as a hardened steel orceramic, although other materials are possible. The crimping blades 14can be configured to move independently of each other or in unison, andcan be configured to collectively contract inwardly towards the centralaxis of the crimping lumen 16 and retract outwardly away from thecentral axis of the lumen 16 in order to adjust the size of the crimpinglumen 16. When contracted, each of the crimping blades 14 can beconfigured to provide an inwardly directed radial force to the insertedstent assembly disposed in the crimping lumen 16. Movement of thecrimping blades 14 can be accomplished using an actuation mechanism (notshown), which can include a number of levers, cams, bearings, connectinglinks, rods, motors, gears, or the like. In use, the crimping apparatus10 may be used to reduce the diameter of a stent inserted within thecrimping lumen 16 and/or may be used to crimp the stent onto anothermember such as a balloon delivery catheter or introducer.

In some embodiments, the crimping apparatus 10 may be equipped with aloading platform (not shown) that can be used to facilitate theinsertion of the stent and stent delivery catheter into the crimpinglumen 16 during crimping and, in some cases, coating. The platform maybe configured to support the stent and/or stent delivery catheter duringloading of the assembly into the crimping lumen 16 for crimping. In someembodiments, for example, the position of the platform can be adjustedto ensure that the stent and/or stent delivery catheter are loadedcentrally within the crimping lumen 16. Such central loading may bebeneficial, for example, to ensure that the radial forces exerted on thestent are substantially uniform during the crimping process.

Each of the crimping blades 14 can include an inner section 22 (e.g., aradially inward portion), a peripheral section 24 (e.g., a radiallyoutward portion), and a length extending from a first end 26 of theapparatus 10 to a second end 28 thereof. The crimping blades 14 may bearranged about a reference circle to form an adjustable crimpingaperture, such as an iris. In some embodiments, the crimping blades 14can be configured and arranged such that each blade 14 has only a singlepoint which lies on the circumference of the reference circle prior tomovement of the blade and is moved along a radius of the referencecircle upon movement of the blade 14.

The crimping blades 14 may have a length that is equal to or greaterthan the length of the stent to be inserted into the crimping lumen 16.In some embodiments, for example, the length of the crimping blades 14may be about 5 cm to 20 cm in length, and more specifically, about 10 cmto 15 cm in length. The length of the crimping blades 14 may deviatefrom these dimensions, however, depending on the particularconfiguration of the stent or other medical device to be crimped, thelength of crimping desired, as well as other factors. Typically, thecrimping blades 14 will have a length as long as or longer than themedical device (e.g., stent) positioned in the crimping lumen 16 suchthat the medical device is reduced uniformly in size along its length.In crimping stents, for example, the blades 14 will typically have alength at least as long as the axial length of the stent, thus ensuringa more uniform crimp along the length of the stent.

The crimping blades 14 may be separated from each other by a small gapG, which may extend along the entire length of the blade 14. In use, thesmall gap G between each of the blades 14 allows the blades 14 to sliderelative to each other. In certain embodiments, the gap G can beconfigured so that the blades 14 slide relative to one another withoutan undue amount of friction. The amount of spacing G between thecrimping blades 14 may depend upon several factors, including the numberof blades 14, the size and shape of the blades 14, the desired size ofthe crimping lumen 16, and the size of the stent assembly.

The crimping lumen 16 may extend longitudinally along an axis from thefirst end 26 of the apparatus 10 to the second end 28 thereof.Alternatively, and in other embodiments, the crimping lumen 16 mayextend longitudinally from the first end 26 of the apparatus 10 towardthe second end 28 but terminate before the second end 28.

The inner section 22 of each of the crimping blades 14 may include oneor more fluid channels 32 that can be connected to a fluid reservoircontaining a drug coating material, lubricious material, adhesive,bonding material, and/or other desired material. In some embodiments,the supply of fluid to the fluid channels 32 can be accomplished via afluid manifold, which can be connected to one or both ends 26,28 of thecrimping apparatus 10. As shown further in FIG. 2, for example, a fluidmanifold 34 can be coupled to or formed integrally with an end 26 of thecrimping apparatus 10 for providing pressurized fluid (e.g., liquid,gel, gas) to one or more of the fluid channels 32.

The fluid manifold 34 can include a number of fluid conduits 36 eachadapted to supply fluid to a particular fluid channel 32 or group ofchannels 32. The number and configuration of the fluid conduits 36 maydiffer, however, from that shown in FIG. 2. For example, although aseparate fluid conduit 36 is shown connected to each of the fluidchannels 32, a single fluid conduit 36 can be connected to the fluidchannels 32 for multiple crimping blades 14. In one alternativeembodiment, for example, each alternating fluid channel 32 can becoupled to a first fluid conduit 36 a for supplying a first fluid to afirst blade 14 a whereas a second fluid conduit 36 b may be used forsupplying a second fluid or gas to another blade 14 b. Otherconfigurations are possible, however. The fluid manifold 34 may includea number of valves that each can be selectively opened or closed todeliver pressurized fluid (e.g., liquid, gel, gas) to selective crimpingblades 14. In some embodiments, for example, a MEMS valve, solenoidvalve, or roller-ball valve may be activated on the fluid manifold 34 toprovide pressurized fluid to one or more crimping blades, as desired.

FIG. 3 is a perspective view showing a crimping blade 14 in accordancewith an illustrative embodiment having a number of fluid openings alongits length. As shown in FIG. 3, each of the crimping blades 14 may havea wedge shape defined by a first side 38, a second side 40, a peripheralportion 42, and a tip 44. The first and second sides 38,40 of thecrimping blade 14 can be curved slightly so as to form a substantiallycircular shaped lumen 16 when the blades 14 are extended in a fullyclosed position. However, in other embodiments the shape of the crimpingblade 14 may differ from that depicted in FIG. 3.

The fluid channel 32 may extend along all or a portion of the length Lof the crimping blade 14 from a first end 46 of the blade 14 to a secondend 48 thereof. As shown in FIG. 3, for example, the fluid channel 32may extend from a first aperture 50 on the first end 46 of the blade 14through the entire length L of the blade 14, terminating in a secondaperture 52 located on the second end 48 of the blade 14. In thisconfiguration, the second aperture 52 may be fluidly coupled to another(e.g., return) fluid manifold, allowing fluid to be recirculated. Such aconfiguration may be useful in some embodiments, for example, to ensurea more uniform pressure differential across the fluid channel 32 to thepressure losses within the channel 32. Alternatively, and in otherembodiments, the fluid channel 32 may extend along only a portion of thelength L of the crimping blade 14, terminating within the interior ofthe blade 14.

A number of openings 54 located along the length of the crimping blade14 and adjacent to the fluid channel 32 can be utilized to spray,extrude, weep, leak, perfuse, or otherwise deliver pressurized fluidfrom within the channel 32 onto the outer surface of the stent and thestent delivery device. The openings 54 can be provided at a location ator near the tip 44 of the crimping blade 14 where contact is made withthe inserted stent. In the illustrative embodiment of FIG. 3, theopenings 54 are disposed at uniform intervals along all or a portion ofthe length L of the blade 14. The uniform spacing of the openings 54allows fluid to be more uniformly applied along the length of the stent.It should be understood, however, that the number and spacing of theopenings 54 may vary from that shown. For example, in some embodimentsthe openings 54 may be non-uniformly spaced along at least a portion ofthe length of the blade 14.

FIG. 4A is a side cross-sectional view showing the crimping blade 14along line 4-4 in FIG. 3. As shown further in FIG. 4A, each of theopenings 54 may be spaced apart from each other by a distance D. In someembodiments, for example, the distance D between each opening 54 may beabout 1 cm to about 3 cm, and more specifically about 2 cm. However, inother embodiments, the distance D between adjacent openings 54 maydeviate from these expressed dimensions. During coating, and as furtherdiscussed herein, fluid F within the fluid channel 32 can be dischargedthrough the openings 54 to coat the outer exposed portions of the stentand/or the stent delivery device. The pressure of the fluid F within thefluid channel 32 may vary depending on the viscosity of fluid F, thetemperature of the fluid F, the transverse dimensions of the fluidchannel 32, the length of the fluid channel 32, as well as otherfactors. In some embodiments, a relatively high pressure (e.g., above100 psi) may be applied to the fluid channel 32 to produce an atomizedspray S of fluid from each of the openings 54, as shown.

FIG. 4B is a side cross-sectional view showing an alternative embodimentof the crimping blade 14 along line 4-4 in FIG. 3. As shown further inFIG. 4B, each of the openings 54 may include a nozzle 45 positionedwithin the openings 54. The nozzles 45 may be chosen to control thecharacteristics of a fluid flow, such as flow rate, speed, directionand/or pressure, as the fluid exits the blade 14. For example, thenozzles 45 may be chosen to direct fluid in a desired pattern from theblade 14 during a crimping process. For instance, in some embodiments, anozzle 45 may be chosen to provide a flat spray pattern, a conical spraypattern, or other desired spray pattern. The nozzles 45 may include anopening or orifice of varying cross-sectional area. For example, aconvergent nozzle may include an opening which narrows from a largerdiameter to a smaller diameter in the direction of fluid flow, whereas adivergent nozzle may include an opening which expands from a smallerdiameter to a larger diameter in the direction of fluid flow. The nozzle45 may also include a convergent section followed by a divergent sectionin the direction of fluid flow.

FIG. 4C is a side cross-sectional view showing an alternative embodimentof the crimping blade 14 along line 4-4 in FIG. 3. As shown further inFIG. 4C, each of the openings 54 may include a ball valve 49 including aball 47 seated within each of the openings 54 of the blade 14. When theforce exerted on the ball 47 by pressure within the channel 32 isgreater than external forces exerted on the ball 47 from exterior of thechannel 32, the ball 47 seats against the opening 54, preventing fluidfrom being discharged out of the channel 32. However, when a force isapplied to the ball 47 exterior of the blade which is sufficient tounseat the ball 47 from the opening 54 (i.e., the applied force isgreater than the force generated by the fluid pressure within thechannel 32) fluid F may be expelled from the blade 14 past the ball 47.For example, during a crimping process, when the ball 47 comes intocontact with a stent as the crimping blades are compressed down on thestent, the stent may force the balls 47 to become unseated, allowing thefluid F to flow out of the channel 32 and into contact with the stent.When the applied force is removed, or reduced, the ball 47 may again beseated against the opening 54, discontinuing the discharge of fluid Fout of the channel 32.

FIG. 5 is a transverse cross-sectional view along line 5-5 in FIG. 3,showing the transverse shape of the fluid channel 32 and openings 54 ingreater detail. As can be seen in FIG. 5, the fluid channel 32 may havea substantially circular or elliptical shape, and in some embodimentscan comprise an insert 56 removably disposed within the interior of thecrimping blade 14. The size of the opening 54 can be made smaller thanthe diameter of the fluid channel 32, forming a convergent/divergentnozzle that acts to throttle fluid pressure at the opening 54 in someinstances. In certain embodiments, the opening 54 can be configured toproduce a spray that exits the opening 54 at an angle sufficient tocover the entire length of the stent.

In some embodiments, and as further shown in FIG. 6, the crimping blade14 may further include a fluid permeable member 58 such as a sponge orother open celled structure disposed within the fluid channel 32 forstoring fluid within the interior of the blade 14. The fluid permeablemember 58 may extend along all or a portion of the length of the fluidchannel 32, and can be configured to act as a storage reservoir forholding fluid within the crimping blade 14.

FIG. 7 is a perspective view showing another illustrative crimping blade60 having a slot or slit 70 along the length of the blade 60. Thecrimping blade 60 may be shaped similar to the crimping blade 14depicted in FIG. 3, having a wedge shape defined by a first side 62, asecond side 64, a peripheral portion 66, and a tip 68. In theillustrative embodiment depicted, the slot or slit 70 may be acontinuous slot or slit 70 formed through the first side 62 of thecrimping blade 60 which may be configured to spray, extrude, weep, leak,perfuse, or otherwise deliver pressurized fluid to the stent and stentdelivery device. The slot or slit 70 may extend along all or a portionof the length of the blade 60 from a first end 72 of the blade 60 to asecond end 74 thereof. In some embodiments, the blade 60 may include twoor more slots or slits 70 extending along a portion of the length of theblade 60. In some embodiments, the slot or slit 70 may extendsubstantially the entire length of the blade 60, except for at theextreme ends 72,74 of the blade 60. In some embodiments, the length ofthe slot or slit 70 (or the combined length of a plurality of slots orslits 70) may be about 60% or more, 70% or more, about 80% or more,about 90% or more, or about 95% or more of the length of the crimpingblade 60.

FIG. 8 is a perspective view showing another illustrative crimping blade76 having a number of larger openings disposed at each end of the blade76. The crimping blade 76 may be shaped similar to the crimping blade 14depicted in FIG. 3, having a wedge shape defined by a first side 78, asecond side 80, a peripheral portion 82, and a tip 84. A first number ofopenings 86 extending through the first side 78 adjacent to the fluidchannel 32 and located between the ends 88,90 of the crimping blade 76can be configured to deliver fluid at a location between the ends of thestent. A second number of openings 92 disposed at or near the opposingends of the fluid channel 32, in turn, can be configured to deliverfluid onto only the ends of the stent. In some embodiments, the size ofthe openings 92 disposed at or near the ends 88,90 can be slightlylarger than the first number of openings 86 to permit more fluid to beejected towards the ends of the stent. In some embodiments, the shape ofthe openings 92 disposed at or near the ends 88,90 can also differ fromthat of the openings 86, as shown. The differences in the size and/orshape of the openings may be used, for example, to spray more adhesiveonto the ends of the stents for a stronger bond to the balloon of theballoon catheter. This may provide for more enhanced stent securement atthe ends of the stent where the stent may be more likely to break offfrom the balloon during delivery. In other embodiments, the differencesin the size and/or shape of the openings may be used to provide athicker and/or additional coating onto the ends of the stents relativeto the thickness and/or amount of coating applied to the central portionof the stent.

FIG. 9 is a perspective view showing another illustrative crimping blade94 having a composite tip along the length of the blade 94. The crimpingblade 94 may be shaped similar to the crimping blade 14 depicted in FIG.3, having a wedge shape defined by a first side 96, a second side 98, aperipheral portion 100, and a tip 102. In the illustrative embodimentdepicted, the crimping blade 94 may have a first portion 104 constructedfrom a first material and a second portion 106 constructed from a secondmaterial, forming a blade 94 having a composite structure. In certainembodiments, for example, the second portion 106 of the compositecrimping blade 94 can be formed from a material that, when contactedwith the outer surface of the stent and/or stent delivery device,provides a layer or coating of adhesive onto the assembly thatfacilitates stent securement. Alternatively, and in other embodiments,the second portion 106 of the composite crimping blade 94 can be madefrom a polymeric material that, when contacted with the outer surface ofthe stent, provides a pharmaceutical and/or therapeutic agent or drugonto the stent assembly.

Referring now to FIGS. 10-13, an illustrative method of crimping andabluminally coating a stent assembly will now be described. As shown ina first view in FIG. 10, a stent 108 disposed onto the balloon 110 of aballoon delivery catheter 112 may be inserted into the crimping lumen 16of the crimping apparatus 10 with the crimping blades 14 in a first(i.e. open) configuration. At this stage, the crimping blades 14 may bein a retracted state such that no radial forces are applied to the stent108. Insertion of the stent 108 into the crimping lumen 16 can beaccomplished, for example, via a loading channel, by a pushing rod, orby some other suitable insertion means.

The catheter 112 may be inserted into the crimping lumen 16 in aretracted configuration with the balloon 110 in a deflated state. Priorto or subsequent to insertion within the apparatus 10, the catheter 112can be inserted into the interior lumen of the stent 108 such that thestent 108 is positioned over the balloon 110. The stent 108 may bepositioned over the balloon 110, for example, by slipping the stent 108over the balloon 110.

In some embodiments, the stent 108 can be releasably coupled to theballoon 110, and thus to the catheter 112, using an adhesive material.For example, an adhesive material having a melting point below that ofthe balloon 110 may be applied between the inner surface of the stent108 and the outer surface of the balloon 110. An illustrative adhesivematerial may be Sorbitol or other biodegradable material. In some cases,the adhesive material may comprise a biocompatible material having amelting point below that of the balloon material (e.g. below 165° F.).The adhesive material may be dispersed in a fluid such as water to forma dilute solution, which may facilitate dispersion of the adhesive. Theadhesive material may be applied between the inner surface of the stentand the outer surface of the balloon, for example, by introducing thematerial within a sheath. For example, a sheath made of a material suchas polytetrafluoroethylene (PTFE) or the like may be positioned overboth the stent 108 and the balloon 110. In some cases, a spray lubricantmaterial such as glycerol can be used to reduce the frictional forces asthe stent 108 is loaded onto the catheter 112 and is crimped thereto.The glycerol can be applied, for example, as part of an aqueoussolution.

The balloon delivery catheter 112 may comprise any catheter known in theart that is appropriate for delivering a stent to a lesion site. In someembodiments, for example, the delivery catheter 112 may comprise apercutaneous transluminal coronary angioplasty (PTCA) balloon cathetercapable of performing an angioplasty procedure. Other delivery devicesare possible, however. The balloon 110 can be made from thermoplasticpolymer such as polyvinyl chloride (PVC), polyolefins (e.g.polyethylene, polypropylene, etc.), polyester (e.g. polyethyleneterephthalate), polyamide (e.g. nylon), polyurethane, ethylene-vinylacetate, thermoplastic elastomers, or the like. Typically, the balloon110 will have a length similar to, or in some cases slightly largerthan, the axial length of the stent 108. The length and diameter of theballoon 108 may be selected based on the dimensions of the stent 108 tobe delivered. Although the step depicted in FIG. 10 illustrates theinsertion of the stent 108 and balloon delivery catheter 112 into thecrimping lumen 16 as a single assembly, it should be understood that thestent 108 and balloon delivery catheter 112 can be inserted into thecrimping apparatus 10 at different stages, if desired.

The stent 108 may have a generally cylindrical shape having afenestrated structure for placement in a blood vessel, duct or lumen.The cylindrical body portion may be formed with a number of wire-likesections that are joined to one another at a number of interstices. Thestent 108 may be made of a wide variety of biocompatible materialsincluding, but not limited to, stainless steel, Nitinol, tantalum,ceramic, polyamides, polyolefins, and non-absorbable polyesters such aspolyethylene terephthalate. One illustrative nonmetallic material ispoly(ethylene oxide), which has a melting point between 140° F. and 160°F. In some embodiments, the stent 108 may be formed from a medical gradestainless steel with the outer surface being plated or otherwiseincluding a coating of platinum to provide for improved visibility witha fluoroscope. The inside surface of the stent 108 may be smooth toreduce friction with the balloon material. The outer surface of thestent 108, in turn, may be relatively rough to prevent slippage of thestent 108 along the vessel surface during stent placement.

Once the stent 108 has been loaded onto the balloon delivery catheter112 and the stent/balloon delivery catheter assembly is positionedwithin the crimping lumen 16 of the crimping apparatus 10, the crimpingblades 14 may then be contracted radially inwardly to crimp theassembly. As shown in a subsequent step depicted generally in FIG. 11,for example, the extension of the blades 14 in a direction indicatedgenerally by arrows P causes the blades 14 to engage the outer portionof the stent 108, producing a radially inwardly force that causes thetips 44 of the crimping blades 14 to come into contact with the stent108 and compress or crimp the stent 108 about the balloon 110 such thatthe stent 108 is compressed or crimped to a smaller diameter around theballoon 110. In some techniques, it may be desirable to repeatedly crimpthe stent 108 by slightly rotating the stent 108 and balloon deliverycatheter 112 a few degrees and then applying a further crimping force tothe assembly. For example, subsequent to a first crimping stepillustrated in FIG. 11, the stent assembly can be rotated about 5degrees, about 10 degrees, about 30 degrees, about 60 degrees, about 90degrees, or about 180 degrees and crimped a second time. If desired, theamount of crimping force applied to the stent assembly can be measuredwith strain gauges attached to the blades 14. In other embodiments,other force measurement devices or means may be used.

As shown in FIG. 12, as a crimping force is maintained on the stent 108by the crimping apparatus 10, a pressurized fluid F may be expelled fromthe channel 32 through the openings 54 toward the stent 108 and/orballoon 110. The fluid F may form a coating on the stent 108 and/orballoon 110. Through such a coating process, the stent 108 may beabluminally coated with a coating. As used herein, “abluminally coated”is intended to refer to the stent 108 being coated on an exterior (i.e.,radially outward surface of the stent 108) while an interior (i.e.,radially inward surface of the stent 108) remains devoid of the coating.

As shown in FIG. 13, once the stent 108 has been sufficiently crimpedand coated, the crimping blades 14 may be retracted away from the stentdelivery assembly to remove the stent delivery assembly from thecrimping apparatus 10. The stent 108 is shown including a coating 116disposed on the outer surface of the stent 108.

To coat the outer surface of the stent 108 and a portion of the catheter112, pressurized fluid may be provided to the fluid channel 32, causingthe fluid to be discharged through the orifices/openings 54 on the tip44 of the crimping blade 14. In some embodiments, the entire outersurface of the stent 108 and the exposed portions of the balloon 110 canbe coated by rotating the balloon delivery catheter 112 and attachedstent 108 within the crimping lumen 16 while fluid F is dischargedthrough the fluid openings 54. If desired, the balloon delivery catheter112 may also be moved longitudinally within the crimping lumen 16. Forexample, the balloon delivery catheter 112 can be moved back and forthlongitudinally within the crimping lumen 16 using a loading channel, orthe like.

FIG. 14A is a perspective view showing an illustrative balloon deliverycatheter 112 and stent 108 having a coating 116 formed by the methoddescribed above with respect to FIGS. 10-13. As shown in FIG. 14A, thecoating 116 may be formed on the outer surfaces of the stent wire 118segments and on the exposed portions of the balloon 110 located withinthe interstices or spaces 120 between the stent wires 118. Thus, as canbe seen, the stent 108 may be abluminally coated with a coating 116,such that the outer surface of the stent 108 may include a coating 116,while the inner surface of the stent 108 (i.e., the surface of the stentcontacting the balloon 110), may remain uncoated.

In other embodiments, coating the stent 108 without rotating the balloondelivery catheter 112 and attached stent 108 within the crimping lumen16 may result in longitudinal stripes of the coating 116 being applied,with adjacent longitudinal portions remaining uncoated.

FIG. 14B is a perspective view showing an illustrative balloon deliverycatheter 112 and stent 108 having a longitudinal striped coating 116formed with the crimping apparatus 10. As shown in FIG. 14B, the coating116 may be formed in discrete longitudinal stripes on the outer surfacesof the stent wire 118 segments and on the exposed portions of theballoon 110 located within the interstices or spaces 120 between thestent wires 118 with adjacent longitudinal portions remaining uncoated.Thus, as can be seen, the stent 108 may be abluminally coated with astriped coating 116, such that the outer surface of the stent 108 mayinclude discrete longitudinal sections having a coating 116 adjacentlongitudinal sections remaining uncoated, while the inner surface of thestent 108 (i.e., the surface of the stent contacting the balloon 110),may remain uncoated.

A variety of stent coatings and compositions may be placed onto thestent 108 may include a therapeutic agent for preventing intimalthickening, smooth muscle tissue proliferation, restenosis,inflammation, coagulation, and/or other conditions at the treatmentsite. An example drug coating may comprise Rapamycin and/or Heparin.Examples of other drugs that can be used are described in U.S. Pat. No.7,225,518, which is incorporated herein by reference in its entirety.The mechanism for delivery of the therapeutic agent can be throughdiffusion of the agent through either a bulk polymer or through pores inthe polymeric structure, or by erosion of a biodegradable coating suchas in the illustrative composite tip 94 in FIG. 9. In some embodiments,one or more of the crimping blades 14 can be configured to provide othermaterials onto the stent and balloon delivery catheter. For example, insome embodiments the crimping blades 14 can be configured to deliver abonding agent that improves adhesive retention of the stent 108 to theballoon 110, or a lubricious material to aid in crossing a lesion withina blood vessel.

If an adhesive is used to help secure the stent 108 to the balloon, theadhesive material forms weak adhesion points at the stent-ballooninterface, forming a bond between the stent 108 and the balloon 110.During delivery, this bond may retain the stent 108 to the balloon 110while permitting the stent 108 to be later released from the balloon 110following inflation and deflation of the balloon 110 at the treatmentsite during stenting.

In an alternative embodiment, once the uncoated stent 108 has beensecured (e.g., crimped) to the balloon delivery catheter 112, thecrimping blades 14 may be retracted away from the assembly a shortdistance, forming a small gap between the outer surfaces of the stent108 and the blades 14. In some embodiments, a coating may be applied tothe stent 108 and/or balloon 110 with the crimping blades 14 of thecrimping apparatus 10 retracted away from and not in contact with thestent 108. As shown in FIG. 15, either prior to or subsequent crimpingthe stent 108 onto the balloon 110, fluid F may be discharged throughthe openings 54 of the crimping blades 14 toward the stent 108, whilethe crimping blades 14 are retracted away from the stent 108. Such aprocess may be found to more completely cover the stent 108 and/orballoon 110 with a coating, if desired.

In some embodiments, the crimping blades 14 may be heated to an elevatedtemperature during the crimping process. In some instances, heatemitting from the heated crimping blades 14 may warm the fluid F toincrease the flowability and/or viscosity of the fluid F to facilitateapplication of the fluid F on the stent 108. In some instances, heatemitting from the heated crimping blades 14 may help cure, solidify,bond, adhere, activate, preserve, convert, or otherwise affect thecoating applied on the stent 108.

Furthermore, in some embodiments, the crimping apparatus 10 may includea first subset of crimping blades 14 including one or more crimpingblades 14 a, and a second subset of crimping blades 14 including one ormore crimping blades 14 b. In some embodiments, the crimping apparatus10 may include additional subsets of crimping blades 14 if desired. Thefirst subset of crimping blades 14 a may be configured to discharge afirst fluid F₁ while the second subset of crimping blades 14 b may beconfigured to discharge a second fluid F₂. If the crimping apparatus 10includes a third or additional subset of crimping blades, the thirdsubset of crimping blades may be configured to discharge a third fluid.

Thus, during a stent coating process using the crimping apparatus 10,multiple coatings may be applied to the stent 108 and/or balloon 110, asdesired. For example, a first coating layer may be applied to the stent108, followed by a second coating layer overlying the first coatinglayer. In some embodiments, a third or additional coating layer maysubsequently be applied to the stent overlying both the first and secondcoating layers.

Thus, in some embodiments, a first coating layer, which may be anadhesive or bonding layer may be overlaid with a second coating layer,which may be a top coat. A third coating layer, which may include atherapeutic agent, may be disposed over the second coating layer.Alternatively, in some embodiments, the first coating layer may includea therapeutic agent, and the second coating layer disposed over thefirst coating layer may be applied to delay the release of thetherapeutic agent included in the first coating layer. Or, the secondcoating layer may include a different therapeutic agent. Thus, thelayering of coatings may be used to stage release of a therapeutic agentor to control release of different agents placed in different layers.

FIGS. 16A and 17A are end views of a stent crimping apparatus 10including a plurality of crimping blades 14 as described above,positioned to define a central crimping lumen 16. The crimping lumen 16shown in FIG. 16A has a first diameter and the crimping lumen 16 shownin FIG. 17A has a second diameter less than the first diameter of thecrimping lumen 16 shown in FIG. 16A. As described above, the diameter ofthe crimping lumen 16 may be changed by retracting and/or contractingthe crimping blades 14 during a crimping procedure.

FIGS. 16B and 17B are perspective views of the relationship of twocrimping blades 14 of the crimping apparatus 10 relative to the diameterof the crimping lumen 16. It is to be understood that, although only twocrimping blades 14 are shown, the additional crimping blades 14 of thecrimping apparatus 10 may interact with adjacent crimping blades in asimilar fashion. As shown in FIG. 16B, when the crimping lumen 16 is ofa sufficient enlarged diameter, the openings 54 of a first crimpingblade 14 a may not be covered or blocked by an adjacent second crimpingblade 14 b. However, as shown in FIG. 17B, when the crimping lumen 16 isreduced in dimension, the openings 54 of the first crimping blade 14 amay be covered or blocked by the second, adjacent crimping blade 14 b.It should be understood that, although not shown, during operation theopenings 54 of the second crimping blade 14 b would additionally becovered or blocked with an additional adjacent crimping blade (notshown). Thus, when the crimping lumen 16 is of the size shown in FIG.17A, the openings 54 of each of the blades 14 of the crimping apparatus10 may be covered or blocked by an adjacent one of the blades 14, andwhen the crimping lumen 16 is of the size shown in FIG. 16A, theopenings 54 of each of the blades 14 of the crimping apparatus 10 may beuncovered or not blocked by an adjacent one of the blades 14.

When the openings 54 of a crimping blade 14 are covered or blocked by anadjacent crimping blade 14, a fluid F located in the channel 32 of theblades 14 will be prevented from being expelled from the openings 54.However, when the openings 54 of a crimping blade 14 are not covered orblocked by an adjacent crimping blade 14, the fluid F located in thechannel 32 of the blades 14 will be permitted to be expelled from theopenings 54.

Thus, for example, during operation a stent may be crimped onto aballoon of a catheter by placing the stent and balloon into the centralopening 16 and contracting the crimping blades 14 of the crimpingapparatus 10 to the crimping lumen 16 diameter shown in FIG. 17A. Atthis diameter, a fluid F is prevented from being expelled from theopenings 54, as the openings 54 are covered or blocked by adjacentcrimping blades 14. After the crimping step has been performed, thecrimping blades 14 may be retracted such that the crimping lumen 16 isenlarged to the diameter shown in FIG. 16A. At this diameter, a fluid Fmay be discharged from the openings 54 of the crimping blades 14 inorder to abluminally coat the stent and/or balloon subsequent to thecrimping step.

In other embodiments, the stent and/or balloon may be coated with thefluid F discharged from the openings 54 of the crimping blades 14 priorto crimping the stent onto the balloon, while the crimping lumen 16 isenlarged to the diameter shown in FIG. 16A. Thus, in such embodiments,once the fluid F is discharged from the openings 54 of the crimpingblades 14, the crimping blades 14 of the crimping apparatus 10 may becontracted such that the crimping lumen 16 is of the size shown in FIG.17A, to thus crimp a stent onto a balloon after coating the stent and/orballoon with a fluid F discharged from the openings 54 of the crimpingblades 14.

FIGS. 18-21 are several side views showing another illustrative methodof crimping and abluminally coating a stent assembly. As shown in afirst view in FIG. 18, a coating apparatus 125 may be inserted into thecrimping lumen 216 of a crimping apparatus 210. The coating apparatus125 may include one or more, or a plurality of openings 154 in fluidcommunication with a lumen 132 of the coating apparatus 125. In someembodiments, the openings 154 may include nozzles or valves similar tothe nozzles 45 or valves 49 of FIGS. 4B and 4C, or another means ofcontrolling fluid discharge from the lumen 132 of the coating apparatus125 through the openings 154.

With the coating apparatus 125 positioned in the crimping lumen 216 ofthe crimping apparatus 210, a fluid F may be discharged from the coatingapparatus 125 to coat the inner surface of the crimping blades 214forming the crimping lumen 216 of the crimping apparatus 210. In someembodiments, it may be desirable to rotate the coating apparatus 125 (asshown by the arrow of rotation of FIG. 17) in order to more fully coatthe entire inner surface of the crimping lumen 216.

As shown in FIG. 19, once a desired amount of a coating 122 is appliedto the inner surface of the crimping lumen 216, the coating apparatus125 may be removed and a stent 108 and/or balloon 110 of a ballooncatheter 112 may placed within the crimping lumen 216 of the crimpingapparatus 210 with the crimping blades 214 in a first (i.e. open)configuration. At this stage, the crimping blades 214 may be in aretracted state such that no radial forces are applied to the stent 108.It is noted that the stent 108 may be loaded onto the balloon 110 of theballoon catheter 112 either before or after placing the stent 108 withinthe crimping lumen 216 of the crimping apparatus 210.

The crimping blades 214 of the crimping apparatus 210 may then becontracted around the stent 108 as shown in FIG. 20, exerting a radiallyinward force on the stent 108 to thereby compress and crimp the stent108 around the balloon 110. The crimping force may be maintained for adesired duration of time to crimp the stent 108 onto the balloon 110. Insome techniques, it may be desirable to repeatedly crimp the stent 108by slightly rotating the stent 108 and balloon delivery catheter 112 afew degrees and then applying a further crimping force to the assembly.For example, subsequent to a first crimping step illustrated in FIG. 20,the stent assembly can be rotated about 5 degrees, about 10 degrees,about 30 degrees, about 60 degrees, about 90 degrees, or about 180degrees, and crimped a second time.

As the stent 108 is being crimped, the coating 122, or a portionthereof, applied to the interior of the crimping lumen 216 may betransferred to the outer surface of the stent 108, thus abluminallycoating the stent 108 with a coating 124.

As shown in FIG. 21, once the stent 108 has been sufficiently crimpedand coated with the coating 124, the crimping blades 14 may be retractedaway from the stent delivery assembly to remove the stent deliveryassembly from the crimping apparatus 10. The stent 108 is shownincluding a coating 124 disposed on the outer surface of the stent 108as a result of the stent 108 contacting the coating 122 applied to theinterior of the crimping lumen 216.

Having thus described the several embodiments of the present invention,those of skill in the art will readily appreciate that other embodimentsmay be made and used which fall within the scope of the claims attachedhereto. It will be understood that this disclosure is, in many respects,only illustrative. Changes can be made with respect to various elementsdescribed herein without exceeding the scope of the invention.

1. A stent crimping and coating apparatus, the apparatus comprising: aplurality of crimping blades positioned in a radial array andcollectively forming a central crimping lumen, the plurality of crimpingblades radially movable to alter the diameter of the central crimpinglumen; each of the crimping blades including a first surface configuredto at least in part define the central crimping lumen; wherein one ormore of the crimping blades includes a stent coating material deliverychannel extending therein for delivering a stent coating material andone or more openings in fluid communication with the stent coatingmaterial channel for expelling a stent coating material from the stentcoating material delivery channel, the one or more openings located atthe first surface of the one or more crimping blades and adapted todischarge a stent coating material into the central crimping lumen. 2.The stent crimping and coating apparatus of claim 1, wherein theplurality of crimping blades are movable between a first, contractedposition in which the central crimping lumen has a first diameter and asecond, retracted position in which the central crimping lumen has asecond diameter greater than the first diameter; wherein in the first,contracted position the one or more openings of the one or more crimpingblades are covered by an adjacent crimping blade; and wherein in thesecond, retracted position the one or more openings of the one or morecrimping blades are uncovered and exposed to the central crimping lumen.3. The stent crimping and coating apparatus of claim 1, wherein each ofthe plurality of crimping blades includes a stent coating materialdelivery channel extending therein and one or more openings in fluidcommunication with the stent coating material delivery channel, the oneor more openings of each of the crimping blades located at the firstsurface of the crimping blade and adapted to discharge a stent coatingmaterial into the central crimping lumen.
 4. The stent crimping andcoating apparatus of claim 3, further comprising a manifold including aplurality of stent coating material conduits, wherein each of the stentcoating material conduits of the manifold is in fluid communication withone or more of the stent coating material delivery channels of theplurality of crimping blades.
 5. The stent crimping and coatingapparatus of claim 1, wherein each of the one or more openings includesa nozzle.
 6. The stent crimping and coating apparatus of claim 1,wherein each of the one or more openings includes a ball valve.
 7. Astent crimping and coating apparatus, comprising: a plurality of movableblades disposed about a reference circle and forming an adjustablecrimping lumen for receiving a stent, each of the blades having a lengthand a stent contacting section; and at least one of the blades includinga stent coating material delivery channel in fluid communication with asource of stent coating material, the stent coating material deliverychannel including at least one opening adapted to discharge a stentcoating material onto a stent positioned within the crimping lumen. 8.The stent crimping and coating apparatus of claim 7, wherein the atleast one opening includes a plurality of openings along the length ofthe blade.
 9. The stent crimping and coating apparatus of claim 8,wherein the plurality of openings are evenly spaced along the length ofthe blade.
 10. The stent crimping and coating apparatus of claim 8,wherein the plurality of openings includes: a first number of openingslocated at opposing ends of the blade; and a second number of openingsspaced along the length of the blade between said ends; wherein thefirst number of openings are larger than the second number of openings.11. The stent crimping and coating apparatus of claim 8, wherein theplurality of openings includes a number of openings disposed adjacent toopposing ends of the blade.
 12. The stent crimping and coating apparatusof claim 7, wherein the at least one opening includes an elongate slotextending along the length of the blade.
 13. The stent crimping andcoating apparatus of claim 7, wherein each blade includes a compositetip including a first portion of a first material and a second portionof a second material dissimilar from the first material.
 14. The stentcrimping and coating apparatus of claim 7, wherein the plurality ofblades includes: a first subset of blades each including a stent coatingmaterial delivery channel in fluid communication with a first source ofpressurized stent coating material; and a second subset of blades eachincluding a stent coating material delivery channel in fluidcommunication with a second source of pressurized stent coatingmaterial.
 15. The stent crimping and coating apparatus of claim 7,wherein the at least one opening includes a nozzle.
 16. The stentcrimping and coating apparatus of claim 7, wherein the at least oneopening includes a ball valve.
 17. The stent crimping and coatingapparatus of claim 7, further comprising a permeable member disposedwithin the stent coating material delivery channel, the permeable memberadapted to absorb pressurized stent coating material from the source ofstent coating material.